Old Word file format *.doc, which compress algorithm did MS use in its old document format?

Question

There is the task in my job. To sign some *.doc files with the certificates, because work process is near with banking account so, that why we need to sign files.

Some information about clients/banks/their contacts etc is including in the *.doc file in the table.

As we know, new Word format uses OpenXML and doesn't use binary serialization, but not the old one.

At this project the *.doc format has been chosen because in Russia (still now), not all the offices at the different cities (not the major one) use old Microsoft Office, where there is no support for *.docx word format.

So, that's why we don't use *.docx

And the question is about the method of binary serialization/compress algorithm of this format. I need to know about the exact algorithm because of juristic rules.

There is an internal format in Russia for products like ISO standard and it has name GOST (ГОСТ) and some algorithms are allowed and some are not.

If we shall use algorithms which aren't allowed for banking document exchange we may got some fines, because it's not just allowed to use it in commercial aims by the law. You may use it in development process or for personal using, but not for the commerce.

So that's why I'm asking about exact method of binary serialization/compress algorithm which is being used in the old Word document file format the *.doc.

Answer 1

The answer may be in this document - found as the second hit in Google on the search term Word file format specification